Detergent compositions manufactured in the form of compacted detergent powder are known in the art. U.S. Pat. No. 5,225,100, for example, describes a tablet of compacted powder comprising an anionic detergent compound which will adequately disperse in the wash water.
Although detergent compositions in the form of compacted granular tablets of various shapes have received much attention in the patent literature, the use of such tablets to provide a unit dose fabric softener which will soften or condition fabrics in the wash cycle without impairing detergency or otherwise compromise the cleaning benefits provided by the detergent composition is not known.
Another possible option for providing a unit dose softener apart from the wash cycle is to introduce the softening ingredients directly into the rinse cycle. But, for this type of product to be effective several practical requirements must be met. To begin with, the size and shape of the unit dose container must be readily compatible with the geometry of a wide variety of rinse cycle dispensers designed for home washing machines in order to insure its easy introduction into the dispenser. Moreover, in common with the general use of rinse cycle softeners, it is necessary to clean the rinse dispenser on a regular basis to avoid residue from accumulating within the dispenser or even, at times, prevent bacterial growth from occurring.
Still further, a unit dose composition for the rinse cycle must be formulated to readily dispense its contents upon contact with water in a period of time corresponding to the residence time of the unit dose in the dispenser, namely, the period of time during which water enters and flows through the rinse cycle dispenser. The aforementioned practical requirements have to date not been successfully met with any commercially available product and hence there remains a need in the art for a unit dose softener capable of activation in the rinse cycle.
Laundry detergent compositions which further include a fabric softener to provide softening or conditioning of fabrics in the wash cycle of the laundering operation are well-known in the art and described in the patent literature. See, for example, U.S. Pat. No. 4,605,506 to Wixon; U.S. Pat. No. 4,818,421 to Boris et al. and U.S. Pat. No. 4,569,773 to Ramachandran et al., all assigned to Colgate-Palmolive Co., and U.S. Pat. No. 4,851,138 assigned to Akzo. U.S. Pat. No. 5,972,870 to Anderson describes a multi-layered laundry tablet for washing which may include a detergent in the outer layer and a fabric softener, or water softener or fragrance in the inner layer. But, these type of multi-benefit products suffer from a common drawback, namely, there is an inherent compromise which the user necessarily makes between the cleaning and softening benefits provided by such products as compared to using a separate detergent composition solely for cleaning in the wash cycle and a separate softening composition solely for softening in the rinse cycle. In essence, the user of such detergent softener compositions does not have the ability to independently adjust the amount of detergent and softener added to the wash cycle of a machine in response to the cleaning and softening requirements of the particular wash load.
Some attempts have been made in the art to develop wash cycle active fabric softeners, typically in powder form. But, these type products are characterized by the same inconvenience inherent with the use of powered detergents, namely, problems of handling, caking in the container or wash cycle dispenser, and the need for a dosing device to deliver the desired amount of active softener material to the wash water. It has now been found that softening of laundry can be effected in the wash cycle with a flexibility which is independent of the detergent dosage, and with great convenience by the consumer by the use of a unit dose wash cycle softener which avoids the common problems associated with the pouring and handling of granular or liquid detergent compositions.